HNO2异构体及其相互转化反应机理的量子化学研究

NO在对流层和平流层的光化学过程起重要作用。HO自由基在清除大气污染物和生成臭氧过程中起着关键作用。HO自由基与NO反应生成非常活泼的自由基HONO,这在气相化学中具有重要地位。Cleaner等发现HNO2存在多种异构体,这些异构体间怎样转化以及其能否稳定存在的问题非常重要。     

对流层夜间化学研究

NO3自由基与N2O5是对流层夜间化学的关键物种。一方面NO3与O3等组分是夜间大气中的重要氧化剂,与它们的反应是生物排放挥发性有机物(VOCs)的主要汇;另一方面NO3与N2O5和雨滴或气溶胶颗粒物发生的异相反应则是大气中氮氧化合物NOx(NO,NO2)的主要清除过程,从而可以减轻对流层臭氧污染。研究它们的化学反应性质及对其进行实地测量,对深入理解大气氧化过程和全面了解区域乃至全球大气自净能力有重要意义。本文总结了近年来有关夜间化学的研究成果,介绍了以NO3和N2O5为中心的基本夜间化学过程、对流层中NO3与N2O5的源与汇以及外场测量技术的最新研究进展,并提出了尚待解决的一些问题。     

对流层夜间化学研究

NO3自由基与N2O5是对流层夜间化学的关键物种。一方面NO3与O3等组分是夜间大气中的重要氧化剂,与它们的反应是生物排放挥发性有机物（VOCs）的主要汇;另一方面NO3与N2O5和雨滴或气溶胶颗粒物发生的异相反应则是大气中氮氧化合物NOx（NO,NO2）的主要清除过程,从而可以减轻对流层臭氧污染。研究它们的化学反应性质及对其进行实地测量,对深入理解大气氧化过程和全面了解区域乃至全球大气自净能力有重要意义。本文总结了近年来有关夜间化学的研究成果,介绍了以NO3和N2O5为中心的基本夜间化学过程、对流层中NO3与N2O5的源与汇以及外场测量技术的最新研究进展,并提出了尚待解决的一些问题。     

可释放一氧化氮纳米材料的研究进展

一氧化氮(NO)是一种内源性双原子分子,在许多生理学和病理学过程中起了关键的调节作用,包括血管平滑肌松弛、免疫反应、神经传递、呼吸作用、细胞凋亡等。NO的生理调节作用在很大程度上依赖于NO释放的位置、时间以及剂量。开发出能够储存NO并且在指定的地点和时间释放需求量的NO的纳米运输平台是非常重要的研究课题。此篇综述,主要介绍近期我们课题组和其他研究人员在NO控制释放以及生物学应用的研究进展。本文首先概述了几类具有应用前景的外源性NO供体,如偶氮二醇烯、亚硝基硫醇、硝基苯和金属亚硝酰化合物。然后,重点讨论了结合NO供体和纳米平台在控制释放NO和生物医学的潜在应用。     

对流层夜间化学研究

NO3自由基与N2O5是对流层夜间化学的关键物种.一方面NO3与O3等组分是夜间大气中的重要氧化剂,与它们的反应是生物排放挥发性有机物(VOCs)的主要汇;另一方面NO3与N2O5和雨滴或气溶胶颗粒物发生的异相反应则是大气中氮氧化合物NOx(NO,NO2)的主要清除过程,从而可以减轻对流层臭氧污染.研究它们的化学反应性质及对其进行实地测量,对深入理解大气氧化过程和全面了解区域乃至全球大气自净能力有重要意义.本文总结了近年来有关夜间化学的研究成果,介绍了以NO3和N2O5为中心的基本夜间化学过程、对流层中NO3与N2O5的源与汇以及外场测量技术的最新研究进展,并提出了尚待解决的一些问题.     

CH_2(~3B_1)与NO的基元化学反应研究

Cth和NO都具有未配对电子,它们之间的反应属于自由基之间的反应．该反应可能经历的通道很多,因此研究这个反应,具有重要的学术价值．另一方面,烃类在燃烧过程中可热解成CH、CW、C：H或CIn等自由基碎片’‘’,亚甲基CW与NO的反应是重要的基元反应之一．除此之外NO是重要的环境污染物,在大气中低浓度NO能够存在较长时间”’,可继续与CHZ自由基发生反应．因此就环境保护方面来说,CIn自由基与NO反应的研究也有较大的现实意义．虽然以前很多人都通过实验测出过CW与NO总反应的速车常数’‘,’－’‘,但关于反应动力学方面的…     

一氧化氮的生物化学及其生理和药理效应

本文论述了一氧化氮（nitric oxide,NO）的生物化学特征及其生理效应和药理效应。NO是生物信使分子和效应分子,NO本身是一个气体分子。NO参与细胞内一系列的生物化学反应,而且,还广泛地影响机体内的生理病理过程。本文阐述了NO在体内的合成机理以及NO供体的基本药理作用,并指出NO生成过多,或者合成障碍,均对机体产生影响。NO相关的新型药物已研制成功,并在临床治疗上初步应用,NO成为生物医学领域研究的热点和前沿课题之一。机体内NO气体信使分子的发现,对于今后其他生物信使的发现提供了重要的启示。     

含Cu复合氧化物对NO和CO吸附和活化的TPSR研究

利用MS－TPD法并结合XRD、化学分析等对催化剂进行了表征，探讨了K2NiF4结构La2-x(Sr，Th)xCuO4±λ系催化剂中三个典型样品LaSrCuO4、La2CuO4和La1.7Th0．3CuO4对NO、CO及CO＋NO等小分子的吸附性能和活化规律。结果表明：NO吸附量的大小与催化剂中氧空位含量有关，吸附强度和脱附峰种类与金属离子氧化态有关。CO在氧缺陷复合氧化物催化剂上的吸附是首先变为碳酸根，并在高温以CO2物种脱出．在NO和CO的共吸附过程中，有关NO的吸、脱性能与单独NO－TPD中NO的吸脱附规律相似，表明NO在NO＋CO共吸附的竞争吸附过程中，优先吸附起决定作用，而受CO的影响较小．NO的吸附是NO活化分解的必要条件．     

266nm脉冲激光光解基质隔离的cis-(NO)2

NO的氧化是大气化学研究的重要课题．CIS－（NO）。是一氧化氮氧化过程的中间体，对其在低温基质条件下的形成和氧化过程研究前文风已作了报导．H。WhiffS等门曾用中压汞灯作为光解光源（220－320urn），研究了ets－（NO）。在Ar低温基质中的光解，产物为N。O和NZO3．CIS－（NO     

秸秆与煤混燃过程中碱金属钾对氮迁移转化的影响

选用经酸洗法脱灰的煤和秸秆制得实验样品。实验采用热重差热分析仪和气相色谱质谱联用仪对不同比例混合的煤和秸秆以及附加不同比例KOH的样品进行燃烧实验,研究秸秆与煤以不同比例混燃过程中碱金属K对NO释放特性的影响。研究结果表明,脱灰样品中参混一定比例秸秆能有效抑制NO释放,且在燃烧过程中NO释放曲线为单峰曲线。低秸秆比例的脱灰混样中,随着K含量的递增,对NO还原的催化作用越强,但含量达到一定值时趋于稳定。混燃气氛中氧气含量越低对还原NO越有利。     

诱导自催化法制备Ni-P超细非晶合金的动力学研究

加入诱导剂(如KBH~4)可使Ni^2+与H~2PO~2^-反应在常温下进行, 便于测量反应中放出的H~2体积, 有利于研究反应的动力学过程及其与反应条件下关系。反应为二级自催化反应, 反应活化能约60kj.mol^-1, pH值不影响反应速率常数, 但pH值越大, 反应诱导期越长, 一般可在40min内完成。由于加入诱导剂能一次成核,生成的Ni-P非晶合金为均匀的球形颗粒。     

Divergent sequential reactions of β-(2-aminophenyl)-α,β-ynones with nitrogen nucleophiles

β-(2-Aminophenyl)-α,β-ynones readily react with nitrogen nucleophiles to give three major types of products, depending on reaction conditions and variation in the nucleophiles. The reaction may lead to simple 1,2-nucleophilic adducts or, at higher temperatures, to a divergent sequential cyclisation giving rise to 2-aryl-4-aminoquinolines by reaction with amines, or to substituted 2-aryl or 2-alkyl-4-alkylidene quinazolines by reaction with amidines. The latter could also be synthesised by reaction of β-(2-aminophenyl)-α,β-ynones with iminochlorides.     

Oxidation of Styrene with Molecular Oxygen in Supercritical CO2

The oxidation of styrene with molecular oxygen catalyzed by PdCl2 CuCl2 has been investigated in supercritical CO2 with a batch reactor. The oxidative system of styrene contains four components at the beginning and seven components during the reaction. The critical temperature, critical pressure, and critical density at different conversions are determined by using a high-pressure view cell. The effect of phase behavior on the conversion and selectivity were studied. Experimental results showed that the critical parameters of the reaction mixture at fixed initial molar ratio changed with the conversion of reactant. The conversion of styrene reached maximum near the critical density of the reaction mixture. Product selectivity also varied with density of reaction mixture and could be tuned to some degree.     

The Action of Carbon Disulfide and Sulfur on Enamines,Ketimines, and CH Acids

The reaction of sulfur, carbon disulfide, and enamines at room temperature leads mainly or exclusively to 3H-1,2-dithiole-3-thiones; these are occasionally accompanied by 2H-1,3-dithiole-2-thiones, which can also be prepared by a modified procedure. Many enamines react with sulfur at room temperature to form thioamides. At about 50°C, enamines of acetophenone give 2-benzylidene-4-phenyl-2H-1,3-dithiol. The action of isothiocyanates and sulfur on enamines leads to the formation of thiazolidine-2-thiones. 2H-Thiopyran-2-thiones can be prepaAred from enamines or dienamines with carbon disulfide at room temperature. The reaction of ketimines (Schiff bases) with carbon disulfide and sulfur yields 3H-1,2-dithiole-3-thiones or isothiazoline-5-thiones. The reaction of alkynes with sulfur and carbon disulfide leads to 2H-1,3-dithiole-2-thiones. Nitriles containing active methylene groups react with carbon disulfide and sulfur to form 5-amino-3H-1,2-dithiole-3-thiones. When isothiocyanates are used instead of CS₂, the reaction leads to δ⁴-4-amino-thiazoline-2-thiones.     

由钛酸盐纳米带水热制备锐钛矿型TiO2纳米带

研究了水热处理具有层状结构的钛酸钠纳米带或钛酸纳米带转化为锐钛矿型TiO₂的制备过程、难易程度和相转化机理. 实验结果表明, 当水热反应温度和时间分别在160 ℃ 和24 h以内, 钛酸钠纳米带很难完全转化为锐钛矿型TiO₂, 若升高反应温度并延长反应时间, 则可制得纯的锐钛矿型TiO₂, 但纳米带形貌被严重破坏; 当水热反应温度和时间分别为160 ℃ 和16 h时, 1次酸洗的钛酸纳米带能够完全转化为锐钛矿型TiO₂, 若钛酸纳米带经过3次强酸浸泡, 则在160 ℃下相转化时间就会缩短到12 h, 所有钛酸纳米带在转化为TiO₂后的形貌仍为纳米带, 但经3次酸浸后生成的TiO₂纳米带表面更光滑. 讨论了钛酸钠纳米带或钛酸纳米带转化为锐钛矿型TiO₂的相转化机理.     

Simultaneous stopped-flow determination of 1- and 2-naphthol

A kinetic method for the simultaneous determination of 1- and 2-naphthol based on their different rate of coupling with diazotized sulphanilic acid in a weakly acid medium is reported. The reaction is performed by a stopped-flow technique and monitored spectrophotometrically at 475 nm. On the basis of this reaction, mixtures of these naphthols can be determined by measuring the reaction rates at two reaction times which gave maximum discrimination between the two naphthols. Theoretical equations are used in order to evaluate the accuracy of the proposed method. Mixtures of these naphthols at the mug/ml level and in 2-naphthol/ 1 -naphthol ratios from 20:1 to 1:5 can be determined with a relative standard deviation of 1.5%. Ternary mixtures of carbaryl, 1-naphthol and 2-naphthol can also be resolved.     

Theoretical Study on the Mechanism of CF2 Reaction with CH2O

The insertion reaction mechanism of CF2 with CH2O was investigated at the B3LYP/6-311G（d）//MP2/6-311G（d） level. The geometric conformations at each stationary point in reaction potential surface were fully optimized and the transition states were verified by intrinsic reaction coordinate （IRC） and frequency analysis. The energies of all reactants were calculated with CCSD（T）/6-311G（d）//G2MP2 methods. Results indicated that the P1 reaction route with difuoroaldehyde as product is the dominant reaction pathway, which exhibits nucleophilic character. According to NBO analysis, the starting point of insertion reaction is the interaction between carbene LP（C3） and formaldehyde π（Cl-O2）. Besides, the thermodynamic and dynamic properties of dominated reaction （1） at different temperature were studied with statistic thermodynamic method and Eyring transition state theory adjusted by Wigner means, from which the proper temperature （500- 1200 K） of reaction （1） could be estimated. Finally, the thermo- dynamic and dynamic properties of insertion reaction mechanisms （CF2, CX2 （X = Cl, Br） with CH2O） were compared and discussed.     

Pressure effects on Friedel-Crafts alkylation reactions in supercritical difluoromethane.

Dielectrometry is used as a novel technique for following the rate of a Friedel-Crafts alkylation reaction in supercritical (sc) difluoromethane. Although the process was not optimized, good product yields were obtained and reaction rates were found to be larger than in CO2 at comparable conditions. The reaction order is determined using the initial rate method and the reaction is shown to be first-order with respect to both anisole and t-butyl chloride. The reaction rate constant is unaffected by pressures above 120 bar but close to the critical pressure the value decreases with increasing pressure. It is also shown that the product distribution for the alkylation of anisole shows significant pressure dependence with substitution at the ortho-position being favored at lower pressures, which is ascribed to hydrogen bonding. This pressure dependency is not observed in sc CO2 or using toluene as a substrate, which supports the idea that hydrogen bonding may be important in the reaction mechanism. The effect of the different reagents and temperature on the rate of the alkylation reaction was also determined.     

Kinetics of Al + H2O reaction: theoretical study

Quantum chemical calculations were carried out to study the reaction of Al atom in the ground electronic state with H(2)O molecule. Examination of the potential energy surface revealed that the Al + H(2)O → AlO + H(2) reaction must be treated as a complex process involving two steps: Al + H(2)O → AlOH + H and AlOH + H → AlO + H(2). Activation barriers for these elementary reaction channels were calculated at B3LYP/6-311+G(3df,2p), CBS-QB3, and G3 levels of theory, and appropriate rate constants were estimated by using a canonical variational theory. Theoretical analysis exhibited that the rate constant for the Al + H(2)O → products reaction measured by McClean et al. must be associated with the Al + H(2)O → AlOH + H reaction path only. The process of direct HAlOH formation was found to be negligible at a pressure smaller than 100 atm.     

C_（60）的胺加成反应和电喷雾电离质谱（ESI－MS）检测

报道了Ｃ６０与１，３－丙二胺和Ｎ，Ｎ－二甲基－１，３－丙二胺的加合反应，反应产物未经预先离子化处理直接用ＥＳＬ－ＭＳ进行检测。由于反应产物从甲苯溶液中析出，避免了生成多胺基加合物，产物以单加成物为主。当加合反应在空气氛下进行时，有加合氧的产物Ｃ６０Ｏｎ（ＮＨ２—ＣＨ２ＣＨ２ＣＨ２ＮＲ２）ｍ（Ｒ＝Ｈ，ＣＨ３）存在。实验发现：Ｎ，Ｎ－二甲基－１，３－丙二胺比１，３－丙二胺更容易与Ｃ６０发生多胺基加成和氧加成反应。通过控制反应条件可制备Ｃ６０二胺的单加成产物。